Liquid ink (i.e., a liquid vehicle with dissolved dye pigment) used in many types of printers is stores in a reservoir and delivered by a capillary tube to a printing nozzle. In a non-impact printer such as a liquid ink jet printer, this ink is forced out of the nozzle in the form of a jet of liquid droplets by heating a resistance element in close proximity to the nozzle. The ink itself is then directed at a printing media such as paper to form lines or dots. The dye is then fixed to the paper by evaporation and absorption.
Unfortunately, because the ink is a liquid composed of a solvent used as the transport vehicle for the ink dye, the nozzle tends to clog due to evaporation of the solvent during periods of non-printing. Typically, this can happen in a period of less than five minutes when the solvent chosen is fast drying such as pure water. Slow drying solvents take longer to evaporate and clog the nozzle, but at the expense of a long drying time for the print on the paper. Also, since dyes in evaporative inks are carried by capillary action into the paper pores during drying, the print density of such inks is quite limited due to the thin layer of dye that remains on the paper surface.
Additionally, because the ink is a liquid, there is also the potential for spillage during handling.
One method of eliminating several of the problems due to the use of liquid ink is the erosion by means of an electric arc of a solid ink directly onto the paper as disclosed by Bovio, et al., in U.S. Pat. No. 4,349,829 issued Sept. 14, 1982. Unfortunately, the Bovio system requires not only the use of an electrically conductive ink, but also a high and potentially dangerous electric potential to move the ink from the reservoir to the paper.